1. Assign roles. Builder, Tester, Recorder, Reporter, Materials Manager. No role = no hands. Rotate every activity.

2. One materials run. Only the Materials Manager visits the supply table. Cuts traffic by 80%.

3. Visual timer. Use a 20-minute build timer projected on the board. When it beeps, hands off — testing begins.

4. Cleanup signal. Play the same 60-second cleanup song every STEM lesson. Pavlovian.

5. Reflection ticket. End every lesson with: "What worked? What would you change?" written on a free exit ticket .

Use the data-collection and computation work in our free games to round out the technology and math pillars of STEM.